Photochromic diaryl-3H-naphthopyrane

ABSTRACT

Disclosed is a photochromic compound having a diaryl-3H-napthopyran structure, which has at the 8-position a nitrogen atom-linked hetercyclus, in which the heterocylcus can also have a HALS compound as a substituent or the heterocyclus itself can be formed as a HALS compound. 
     Furthermore a photochromic compound is described having a diaryl-3H-naphtopyran structure which has at the 8-position an N-atom linked and an alkyl-bridge linked HALS compound.

This application is a national stage application (371) ofPCT/DE96/02049, filed on Oct. 28, 1996.

TECHNICAL FIELD

The present invention relates to photochromic diaryl-3H-naphthopyrans.

STATE OF THE ART

Photochromic compounds possess the property that they change colorreversibly under the influence of light containing a certain amount ofultra-violet radiation, such as for instance sunlight or the light froma mercury vapor lamp. This coloring is due to a bond opening in thepyran ring of the photochromic naphthopyran induced by the high-energyultra-violet light. After removing the ultraviolet radiation source, thecompound returns to its original closed state.

A variety of classes of photochromic compounds have been known for sometime and are used in various applications requiring reversiblelight-dependent coloring, by way of illustration by means of theultraviolet part of the sunlight.

A variety of methods for coloring plastic articles using photochromiccompounds are described in the state of the art. With regard to thisreference is made , by way of example, to U.S. Pat. No. 4,286,957, DE-A35 16 568 and EP 0 227 337 B1.

The basic chemical structure of benzopyrans and naphthopyrans isdescribed by Becker in U.S. Pat. No. 3,567,605. However these compounds,which were patented as early as in 1971, are hardly of significance foruse in the production of photochromic articles, because their color isdependent on irradiation with ultraviolet light only at temperatures inthe -40° C. range.

Moreover, U.S. Pat. No.: 5,066,818 discloses that photochromic compoundsthat are suited for use at normal temperatures are obtained byintroducing at least one ortho-substituted phenyl group in the3H-position of the pyran ring. These compounds can be employed, by wayof illustration, in optical lenses or other transparent plasticarticles.

A further development of the general naphthopyran compounds known fromU.S. Pat. No. 5,066,818 is described in U.S. Pat. No. 5,369,158.According to this printed publication, the photochromic naphthopyranspossess particularly advantageous properties if they are substituted atthe 8-position of the naphthalene portion. Compared to othernaphthopyrans with substitutents in the 5-, 7- or 9- position, thesephotochromic compounds exhibit a considerable bathochromic shift of theabsorption maximum in the activated as well as in the non-activatedstate. Furthermore, this shift leads to increased darkening velocity andgreater optical density in the photochromic compound.

The naphthopyrans of U.S. Pat. No. 5,369,158 have the followingstructure: ##STR1## with R5 and R9 being H, C₁ -C₄ alkoxy or C₁ -C₄alkyl, R8 being halogen, C₁ -C₅ acyloxy, benzoyloxy, methoxybenzoyloxyor di(C₁ -C₅)alkylamino or LO-, wherein L is C₁ -C₁₂ alkyl, C₆ -C₉ aryl(C₁ -C₃) alkyl, C₅ -C₇ cycloalkyl or C₅ -C₇ cycloalkyl substituted by C₁-C₄ alkyl and B and B' are substituted or unsubstituted phenyl ornaphthyl, pyridyl, thienyl, benzothienyl, furyl or benzofuryl, with thesubstituent or substituents being C₁ -C₄ alkyl, C₁ -C₄ halogen alkyl, C₁-C₄ alkoxy, C₁ -C₄ -alkoxy(C₁ -C₄) alkyl, di (C₁ -C₅) alkylamino orhalogen provided that at least one of the residues B or B' issubstituted or unsubstituted phenyl or B and B' together form anadamantane residue.

Furthermore this printed publication mentions that ultra-violetabsorbers or stabilizers like hindered amine functions (HALS) orsingulet oxygen removers can be added to the photochromic compounds inorder to improve the stability and the lifetime.

Photochromic naphthopyrans having an amide substituent, which can be aacyclic amide, at the 9-position of the basic naphthopyran structure areknown from PCT/WO 95/00867. This substitution causes the absorptionmaximum to shift into the longwave range but also results in diminishedmaximum darkening and slower darkening velocity.

DESCRIPTION OF THE INVENTION

The object of the present invention is the description and the synthesisof photochromic compounds which possess improved properties compared tothe compounds known from the state of the art, such as a goodphotochromic effect, a high darkening velocity, intense maximumdarkening, a longwave absorption in the activated state, a rapidlightening velocity and a long lifetime.

An element of the present invention was understanding that suited forsolving this object :is a photochromic compound, which has adiaryl-3H-naphthopyran structure having at the 8-position a cyclicnitrogen base linked via a nitrogen atom, having the followingstructure: ##STR2## with R1 and R2: hydrogen, C₁ -C₄ alkyl or C₁ -C₄alkoxy

B and B': ##STR3## with R and R': C₁ -C₄ alkyl, C₁ -C₄ halogen alkyl, C₁-C₄ alkoxy, C₁ -C₄ alkoxy (C₁ -C₄) alkyl, di(C₁ -C₅, alyklamino,halogen, with halogen=F, Cl, Br

and p, q: 0, 1, 2

Y: --O--, --S--, N--R" with R"=C₁ -C₆ alkyl, phenyl, benzyl

--(CZ₂)--,

with Z═H, C₁ -C₆ alkyl, and two Z also together C₅ -C₇ cycloalkyl

and m being an integer from 3 to 7

with at least (m-1) residues Y being --(CZ₂)--.

These compounds are superior in various respects to the compounds knownfrom the state of the art.

The invented introduction of a cyclic nitrogen base at the 8 position ofthe diaryl-3H-naphthopyran improves the electron stabilizing effect ofthe substituents known from the state of the art, such as by way ofexample --OR, due to a stronger electron donator effect of the cyclicnitrogen base. This increased stabilization surprisingly leads only to asmall shift of the absorption maximum of the non-activated form of thephotochromic compound but to a great bathochromic shift of theabsorption maximum of the activated form of the photochromic compound.

The introduction of a cyclic nitrogen base instead of analog compoundshaving an open amine structure known from the state of the art improvesthe lifetime of the photochromic compound.

Especially advantageous is if, according to claim 2, a class ofcompounds known as hindered amine light stabilizer (HALS) is introducedat the 8-position of the diaryl-3H-naphthopyran structure. Thesesubstances, whose effect is based on the capture and inactivation ofradicals, are utilized as light protection means in polymer materials.The conventionally employed HALS have two essential structural features.First, they have a free amine function (N--H), and second they possesssteric hindrance, greatly space-filling groups in the immediate vicinityof this free amine function.

Recently, polymer substances of the HALS type have also been developed.These polymer substances of the HALS type no longer have a free aminefunction, but rather are polymerized via a substituent at the nitrogen.However, like the conventional HALS they possess steric hindrance groupsat the ortho-position for the amine function. Although the lightprotective effect of these new substances does not attain the quality ofconventional HALS having a free amine function, it suffices for usingthese substances in the embodiment of the present invention described inclaim 2.

The introduction of the HALS substances into the basicdiaryl-3H-naphthopyran structure by means of the N-atom linked cyclicnitrogen base occurs according to the present invention in such a mannerthat the ring of the cyclic nitrogen base is provided with the HALSproperties. In addition to the N-atom, which represents the linkingpoint to the diaryl-3H-naphthopyran structure, the cyclic nitrogen basehas an amine function and at the ortho-position to this amine group ithas a greatly space-filling substituent, such as by way of illustrationtetramethyl, tert.-butyl or other branched or long-chain groups.

The use of these substances, which are known as HALS substances, forlight stabilization is described for instance in EP 0313 941 A1 or inthe journal "farbe+lack", 95. Jahrgang, 10/1989, pp. 715 ff. DasTaschenbuch der Kunststoff Additive by Gachter/Muller, 2nd edition, CarlHanser Verlag, describes on pp. 144 ff. the use of these HALS asadditives for polymer mixtures.

However, on the basis of this literature, known is only to add thesubstances to the polymer materials. None of the documents, however,mentions entering these compounds in a modified form of a cyclicnitrogen base into other molecules, such as by way of illustrationphotochromic dyestuffs.

The described HALS compounds, which for example are obtainable under thetradenames TINUVIN, CHIMASORB, CYASORB; SPINUVEX or HOSTAVIN, areusually added to the photochromic compounds in concentrations of 0.01 to5% in order to increase their lifetime.

Introducing these substances directly into the diaryl-3H-naphthopyranstructure at the 8-position, an N-atom linked cyclic nitrogen base fromthe hindered amine light stabilizer (HALS) compound, obviates addingthese stabilizers later, thereby facilitating the use of the inventedcompounds in the manufacture of plastic articles having photochromicproperties. The lifetime of the photochromic compounds is also improved,because the stabilizer is entered directly into the molecule. Undesiredeffects such as wrong dosage or demixing are thus prevented. In this wayit is always ensured that an active HALS is always located in thevicinity of the dyestuff molecule. In conventional addition, thisrequires very high concentrations, which are partly no longer soluble inthe monomer.

Just as advantageous is to add the HALS compounds not immediately intothe cyclic nitrogen base, but rather link them as a substituent directlyor via an alkyl bridge --(CX2)n--, with X═H, C₁ -C₆ alkyl, and n is aninteger from 0 to 6, to the cyclic nitrogen base.

Moreover, it was recognized that suited for solving the object of thepresent invention are also substances which have a cyclic nitrogen baselike the type of the HALS compounds which is linked via an alkylbridge--(CX₂)_(n), with X═H, C₁ -C₆ alkyl, and is an integer from 0 to6, with one N-atom being linked at the 8-position of thediaryl-3H-naphthopyran structure. The third valence of the N-atom can befree or can be substituted by C1-C₆ alkyl.

Although in this way the electron stabilizing properties of the cyclicnitrogen base are slightly weakened by the greater distance to thediaryl-3H-naphthopyran structure, the invented compounds are superior tothe state of the art compounds due to the simultaneously occurringlight-stabilizing effect of the HALS compound.

Furthermore, as described the cyclic nitrogen base can also have acondensated on aromatic or heteroaromatic system or a condensated-oncycloalkyl ring.

Examples for the cyclic nitrogen bases, which are introduced at the8-position of the diaryl-3H-naphthopyran structure via the N-atom areazetidine, pyrrolidine, piperidine, hexahyroazepine, heptamethylimine,morpholine, thiomorpholine, N-methylpiperazine, N-phenylpiperazine,indoline, isoindoline, benzoindoline, tetrahydrochinoline,tetrahydroisochinoline and N-methylimidazolidine.

What is claimed is:
 1. A photochromic compound with adiaryl-3H-naphthopyran structure and an N-atom linked cyclic nitrogenbase at the 8-position, having the formula ##STR4## with R₁ and R₂ :hydrogen, C₁ -C₄ alkyl or C₁ -C₄ alkoxy,B and B': ##STR5## with R andR': C₁ -C₄ alkyl, C₁ -C₄ halogen alkyl, C₁ -C₄ alkoxy, C₁ -C₄ alkoxy (C₁-C₄) alkyl, di(C₁ -C₅) alkylamino, halogen, with halogen═F, Cl, Br; andp and q: 0, 1, 2, Y: --O--, --S--, N--R" with R"═C₁ -C₆ alkyl, phenyl orbenzyl, or --(CZ₂)--, with Z═H or C₁ -C₆ alkyl, and two Z alsotogether.tbd.C₅ -C₇ cycloalkyl, wherein R" or one Z may be a hinderedamine light stabilizer (HALS) compound or a hindered amine lightstabilizer compound linked via an alkyl bridge --(CX₂)n--, with X═H orC₁ -C₆ alkyl, and n is an integer from 0 to 6; and m: an integer from 3to 7, with at least (m-1) of the groups Y being --(CZ₂)--.
 2. Aphotochromic compound with a diaryl-3H-napthopyran structure, whereinthat said compound has at the 8-position an N-atom linked cyclicnitrogen base derived from a hindered amine light stabilizer (HALS)compound.
 3. A photochromic compound with a diaryl-3H-naphthopyranstructure and an N atom linked nitrogen base at the 8 position, saidcompound having the formula ##STR6## with R1 and R2: hydrogen, C₁ -C₄alkyl or C₁ -C₄ alkoxy;B and B': ##STR7## with R and R': C₁ -C₄ alkyl,C₁ -C₄ halogen alkyl, C₁ -C₄ alkoxy, C₁ -C₄ alkoxy (C₁ -C₄) alkyl, di(C₁-C₅) alkylamino, halogen═F, Cl, Br; and p and q: 0, 1, 2: wherein theN-atom in the 8-position is linked to a hindered amine light stabilizer(HALS) compound via an alkyl bridge --(CX₂)_(n) --, with X═H or C₁ -C₆alkyl, and n is an integer from 0 to 6, the N-atom having as a furthersubstituent H or C₁ -C₆ alkyl.
 4. A photochromic compound according toclaim 1, wherein said cyclic nitrogen base at the 8-position has beenring-condensed with an aromatic, heteroaromatic or cycloalkyl ring.
 5. Aphotochromic compound according to claim 1, wherein said cyclic nitrogenbase is azetidine.
 6. A photochromic compound according to claim 1,wherein said cyclic nitrogen base is pyrrolidine.
 7. A photochromiccompound according to claim 1, wherein said cyclic nitrogen base ispiperidine.
 8. A photochromic compound according to claim 1, whereinsaid cyclic nitrogen base is hexahydroazepine.
 9. A photochromiccompound according to claim 1, wherein said cyclic nitrogen base isheptamethylimine.
 10. A photochromic compound according to claim 1,wherein said cyclic nitrogen base is morpholine.
 11. A photochromiccompound according to claim 1, wherein said cyclic nitrogen base isthiomorpholine.
 12. A photochromic compound according to claim 1,wherein said cyclic nitrogen base is N-methylpiperazine.
 13. Aphotochromic compound according to claim 1, wherein said cyclic nitrogenbase is N-phenylpiperazine.
 14. A photochromic compound according toclaim 4, wherein said cyclic nitrogen base is indoline.
 15. Aphotochromic compound according to claim 4, wherein said cyclic nitrogenbase is isoindoline.
 16. A photochromic compound according to claim 4,wherein said cyclic nitrogen base is benzoindoline.
 17. A photochromiccompound according to claim 4, wherein said cyclic nitrogen base istetrahydroquinoline.
 18. A photochromic compound according to claim 4,wherein said cyclic nitrogen base is tetrahydroisoquinoline.
 19. Aphotochromic compound according to claim 1, wherein said cyclic nitrogenbase is N-methylimidazolidine.
 20. A photochromic compound according toclaim 2, wherein said cyclic nitrogen base is2,2,6,6-tetramethylpiperazine and is linked via said nitrogen atom withsaid diaryl-3H-naphthopyran at the 4-position.